Catalyst assembly for use in anode gas oxidizing systems of high temperature fuel cells

Abstract

An oxidizer catalyst assembly for use in a fuel cell system for oxidizing anode exhaust gas and in which a first catalyst member is situated along a gas flow path and a second catalyst member is situated along the gas flow path following the first catalyst member. Each of the catalyst members includes a plurality of channels for passing the gas therethrough and an oxidizing catalyst deposited in the channels. The channel density of the channels of the second catalyst member is greater than the channel density of the channels of the first catalyst member and the channel width of the channels of the second catalyst member is less than the channel width of the channels of the first catalyst member.

1. A fuel cell system including an oxidizer catalyst assembly for oxidizing an anode exhaust output from an anode of a fuel cell of the fuel cell system, said oxidizer catalyst assembly comprising: a first catalyst member arranged along a gas flow path; a second catalyst member arranged along said gas flow path following said first catalyst member; each of said first and second catalyst members including a plurality of through channels for passing gas therethrough and an oxidizing catalyst in each of said through channels; and said channels of said second catalyst member having a channel density which is greater than the channel density of said channels of said first catalyst member and a channel width which is less than the channel width of said channels of said first catalyst member. 
     
     
       2. A fuel cell system in accordance with  claim 1 , wherein said second catalyst member is spaced from said first catalyst member by a distance n. 
     
     
       3. A fuel cell system in accordance with  claim 2 , wherein said distance n is between 0 and 6 inches. 
     
     
       4. A fuel cell system in accordance with  claim 1 , wherein:
 said channel density of the channels of said first catalyst member is 200 channels per square inch or less and said channel density of the channels of said second catalyst member is 250 channels per square inch or more; and 
 said channel width of said channels of said first catalyst member is 0.071 inch or greater and said channel width of said channels of said second catalyst member is 0.063 inch or less. 
 
     
     
       5. A fuel cell system in accordance with  claim 4 , wherein said channel density of the channels of said first catalyst member is 100 channels per square inch and said channel density of said channels of said second catalyst member is 400 channels per square inch. 
     
     
       6. A fuel cell system in accordance with  claim 1 , wherein each of said catalyst members comprises one of a ceramic monolith body and a metallic monolith body. 
     
     
       7. A fuel cell system in accordance with  claim 6 , wherein the monolith body of each of said catalyst members comprises an oxidizing catalyst coating. 
     
     
       8. A fuel cell system in accordance with  claim 7 , wherein the monolith body each of said catalyst members comprises a substrate coating under the oxidizing catalyst coating. 
     
     
       9. A fuel cell system in accordance with  claim 8 , wherein said oxidizer catalyst is at least one of Pt, Pd and Rh and said substrate coating is at least one of alumina, silica, zirconia, alumina-ceria and ceria.